The present invention relates to an improved method and apparatus for the vertical registration or alignment of electrical components, such as multi-lead chip members, over pad areas of receptor members such as printed circuit boards, each said pad area comprising a contact area designed to be contacted with and soldered to one of said leads to integrate the chip member into the printed circuit loop.
It is known to provide vision system devices for supporting multi-lead chip members vertically over pad members and for interposing a beam splitter cube therebetween for purposes of viewing and aligning the underside of the chip member with the surface of the pad member, such viewing being done through a solid state camera and monitor system providing a video screen image. Such known devices have been commercially-available under the trademarks Model 4460 M Rework Station available from Semiconductor Equipment Corp., Moorpark, CA, Conceptronic Rover, Explorer and Caps Pick and Place Systems available from Conceptronic, Exeter, NH.
While such systems and devices are designed for the same purposes as the present systems, they have the disadvantage of providing video screen images of the chip member and the pad member to the operator for purposes of facilitating adjustment of the X, Y, theta and Z axes for alignment. Such video images are of relatively poor quality, sharpness and fixed contrast, which makes it difficult for the operator to visually distinguish between the leads and the pad areas, particularly in cases where there is a color contrast between the component and the pad member.
It is also known to provide vision system devices which give the operator a direct three dimensional view of the underside of the component and the surface of the pad member through a beam splitter cube and a stereo microscope means, for the present purposes. Reference is made to the Model DRS-22 Surface Mount System available from Air-Vac Engineering Company, Inc., Milford, CT, the present applicant. While such devices provide a superior stereo view of the component and the pad to the operator for alignment purposes, they do not permit any adjustment of the visual contrast between the component and the pad member, which makes it difficult for the viewer to distinguish between the component and the pad member, particularly in cases where there is a color contrast therebetween. Also the view provided to the operator varies significantly with the ambient light even though the apparatus incorporates external small halogen-type lamp source, the light from which illuminates both the component and the circuit board. Such light variations are dependent upon the location of the apparatus and upon variations of the ambient light even when the apparatus is only used in a single location.